#include<stdio.h>
#include<pthread.h>
int sum=0;
pthread_mutex_t mutex;
void *thread(void*)
{
   int i;
   for(i=0;i<1000000;i++)
       {
           pthread_mutex_lock(&mutex);
           sum+=1;
          pthread_mutex_unlock(&mutex);   
       }
}
int main(void)
{
     pthread_t tid1,tid2;
     pthread_mutex_init(&mutex,NULL);
     pthread_create(&tid1,NULL,thread,NULL);
     pthread_create(&tid2,NULL,thread,NULL);
     pthread_join(tid1,NULL);
     pthread_join(tid2,NULL);
     printf("1000000+1000000=%d\n",sum);
     return(0);
}
